1. Field of the Invention
The present invention relates to a side air bag system that protects a side of an occupant's head at a side crash or a rollover of a vehicle, and, more particularly to a side air bag system for head protection, applied to a vehicle whose roof can be folded down.
2. Description Of The Related Art
An air bag system is often provided in a vehicle interior to protect the occupant's head in an emergency such as a collision and a rollover. In a convertible roof vehicle when the roof is closed, the occupant is seated with his/her head slightly tilted downward due to a small overhead space in a closed-roof condition, especially if the occupant is in the rear seat of the vehicle. When the roof is open, the occupant is usually seated with his/her head lifted in a normal sitting posture. Accordingly, an occupant's head position depends in large part on whether the roof is closed or open.
In order to adapt the air bag system to the open-roof and closed-roof conditions respectively, the air bag system in the related art has to be separately provided at the respective positions corresponding to the above two head positions where the occupant's head tilts downward when the roof is closed and the occupant's head is lifted when the roof is open. Such an installation structure in which the air bag systems are separately provided at upper and lower positions is disclosed, for example, in Japanese Patent Provisional Publication No. 5-139232 (“JP 5-139232”).
In JP 5-139232, an air bag system having an upper air bag and a lower air bag is provided in the interior. In more detail, the upper and lower air bags are installed at an interior side of a side door of a normal vehicle, namely the vehicle whose roof is fixedly provided, to be spaced apart from each other at a predetermined distance.